1. Field of the Invention
The present invention relates to a navigation system, and more particularly, to a re-routing apparatus and method for calculating an optimum alternative path to an original path from a position deviated from the original path and then performing a re-routing for a path to a destination according to the calculated result when a movable body receiving path guidance through a navigation system has deviated from the original path.
2. Description of the Related Art
In general, movable bodies such as ships, airplanes and cars, may be provided with navigation systems. A navigation system receives radio signals, representing coordinates, e.g., latitude, a longitude, an altitude, etc., from a plurality of satellites included in the Global Positioning System (GPS), and calculates a current position of a movable body. Further, such a navigation system displays geographical information including the current position of the movable body according to map data stored in advance. That is, such a general navigation system provides drivers with various information necessary for driving, by means of information received from the GPS. For example, it displays on a screen a current speed of movement, a path of movement, set by a driver before driving, and an optimum path to a destination.
FIG. 1 is a diagram showing the make-up of a conventional navigation system. Such navigation system includes a GPS satellite 10, a mobile terminal 30, for instance, cell phone, communicating with a wireless network 40 and a navigation terminal 20, for instance, a navigation kit, communicating with the GPS satellite 10 and the mobile terminal 30 in order to provide a driver with current position information and travel information of a movable body. In the exemplary navigation system the navigation terminal 20 and the mobile terminal 30 are provided in a car.
The navigation terminal 20 receives the position information of the movable body from the GPS satellite 10 and analyzes the position of the movable body. Further, the navigation terminal 20 transmits the position information to the mobile terminal 30 in order to provide the driver with the travel information of the corresponding position.
The mobile terminal 30 functions as an interface between the navigation system and driver. For instance, when the driver requests current position information of the movable object and a path to a destination by means of the mobile terminal 30, the navigation system provides corresponding information to the driver through a display unit (not shown) of the mobile terminal 30. Generally, the information thus provided through the display unit of the mobile terminal 30 is image information, and sound information is provided to the driver through a speaker installed on the navigation terminal 20.
For this, the mobile terminal 30 performs data transmission/reception with an information server 50 such as a traffic server, which is connected through the wireless network 40.
In general, the information server 50 constructs the travel information in a predetermined data format such as Route Guidance Information (RGI) data, and transmits the constructed data format to the navigation terminal 20 via the mobile terminal 30. The navigation terminal 20 analyzes the data format and provides the driver with the travel information of a corresponding position. In this case, the RGI data is the travel information of a link unit.
FIG. 2 illustrates a data format of RGI data 60 utilized conventionally in a navigation system. The RGI data 60 includes a link number field 61, a travel distance field 62, a road type field 63 and a travel information field 64. Each field stores the following information. The link number field 61 stores an identification number regarding the link, the travel distance field 62 stores an entire travel distance of a corresponding link, the road type field 63 stores road types of the corresponding link such as a local highway, a national highway or an express highway. Further, the travel information field 64 stores travel information regarding what is in front of a movable body, such as a left turn 200 m in front and a sharp curve 300 m in front. The RGI data 60 may further include a field for storing additional service information regarding a corresponding path.
FIG. 3 is a flow chart of a path guidance method according to a conventional embodiment. First, if a user inputs a destination to the mobile terminal 30 in order to obtain optimum path information for a predetermined destination, the mobile terminal 30 transmits, in step S10, current position information sent from the navigation terminal 20 and, in step S11, the destination information, to the information server 50 via the wireless network. In the present case, the navigation terminal 20 detects the current position information of the movable object by means of a GPS receiver and transmits the detected result to the mobile terminal 30. The information server 50 calculates in step S12 an optimum path to a corresponding destination by using real-time traffic information stored in advance, and transmits first RGI data, which has been generated by the result from the calculation, to the navigation terminal 20 via the mobile terminal 30 in steps S13, and S14 respectively. In the present example, the information server 50 receives the real-time traffic information from an outside server such as the traffic server, or manages the information after collecting the information itself.
Further, in step S15 the navigation terminal 20 tracks a current position of a movable body by comparing the first RGI data with sensor data collected by itself, and in step S116 transmits path guidance information according to the result from the tracking, to the mobile terminal 30. Further, on the basis of the result from the tracking, the navigation terminal 20 judges whether the movable body has deviated from a path transmitted from the information server 50 or not. When a deviation is detected in step S17, the navigation terminal 20 transmits the deviation information such as a deviated position information to the mobile terminal 30 in step S18.
The mobile terminal 30, which has received the deviation information, transmits the deviation information to the information server 50 after connecting to the information server 50 via the wireless network, in order to obtain an optimum path from the position deviated from the original path, hereinafter, referred to ‘deviated position’ to a destination and provide the obtained optimum path to the navigation terminal 20 in step S19.
In step S20 the information server 50 recalculates the optimum path to the destination from the deviated position by means of the deviation information and the already stored destination information and transmits second RGI data, which has been generated as a result of the calculation, to the navigation terminal 20 via the mobile terminal 30 in steps S21 and S22 respectively. That is, in the prior art, when the movable body has deviated from an initial path transmitted from the information server 50, the navigation terminal 20 must receive the optimum path from the deviated position to the destination again, only after reconnection to the information server 50 via the mobile terminal 30.
Accordingly, in the prior art, there is a problem in that the navigation system user must defray a communication cost for reconnection to the information server 50. Further, in the conventional navigation system, it takes too much time for a user to reconnect to the information server 50 and receive a new path, thereby increasing inconvenience to the user. Moreover, since the movable body goes on moving until it receives the new path, there is a high possibility that another deviation from the new received path may occur.